Egyptian police have shot dead two protesters in Suez, while crowds rallied outside Cairo's interior ministry building overnight as anger spread over the deaths of 74 people in a bloody riot at a football stadium.

The response to the scenes after the match on Wednesday night in the Mediterranean city of Port Said has taken on a wider political dimension amid claims police at best did nothing to prevent the violence and, at worst, actively helped instigate it.

In Suez a crowd of around 3,000 people demonstrated outside police headquarters after news spread that one of the victims came from the city.

The riot started when supporters of Al Masry, the home team, stormed through open gates leading onto the pitch, first chasing players from Cairo's Al Ahly club and then their supporters. Police responded with teargas and opened fire, witnesses said, with officials saying two people had died.

Thousands more held protests on Thursday in front of the interior ministry, which has responsibility for the police. Demonstrators threw rocks, and police responded with teargas, with almost 400 protesters needing treatment.

The aftermath of the riot threatens to spiral into a more general political crisis for Egypt, almost a year since the toppling of Hosni Mubarak, with anger focused particularly on the widely distrusted police and the military now in charge.

The lack of security at the Port Said stadium, which allowed Al Masry supporters to attack rival fans chase them against closed exit gates, where many were crushed, caused heated debate in the newly elected parliament, with some MPs claiming security officials helped cause the violence.

While Egypt's military rulers were quick to blame football hooliganism, a group of hardline Al Ahly fans, known as ultras, accused the police of intentionally letting rivals attack them because of their historic antipathy to the security forces and their role at the forefront of anti-Mubarak protests a year ago. Many ultras were among those protesting outside the interior ministry.

Some witnesses at the stadium reported seeing people in the Al Masry stands armed with clubs and knives after police failed to carry out usual pre-match searches. TV footage of the riot showed men on the pitch with clubs and poles.

"The atmosphere was very aggressive," he said. "There were opposition fans walking up and down unchallenged in front of our bench during the game and the police did nothing."

Islam Saeed, a member of the Al Ahly ultras, said nobody had attempted to control the crowd as it grew ever more restive as Wednesday's game progressed.

"Hundreds would storm the pitch after every goal, so we could sense what was going to happen," he said. "There was a huge lapse in security. The police non-intervention was very strange, there was practically no security outside the stadium, and inside it they didn't do anything when events escalated.

"This was gross security incompetence, coupled with the barbarity of some supporters. This has been happening for the past five years, but security always intervened. They didn't this time. If you allow this to happen, then you are liable for the deaths."

Members of the Cairo-based ultras vowed to hold Egypt's military rulers, the supreme command of the armed forces, accountable for the deaths, and said they were planning a series of rolling demonstrations across the country for the rest of the week.

Egypt's previous worst football incident was in 1974, when 49 people were trampled to death at a match in Cairo.

Egypt's parliament has accepted the resignation of Port Said's civilian governor and the region's security chief. It also pledged to look into the allegations of excessively lax security for a game between two teams known to be arch-rivals and whose fans had clashed before.

The Egyptian Football Association was also sacked en masse, as was the security team responsible for the stadium. Some MPs blamed the interior minister, Mohammed Yousef, for allowing lapses and they gave him one week to restructure the ministry.

Morgue officials in Port Said said most of the dead had been killed by blows, falls or as a result of being crushed.